int geuss(int num);

class Solution
{
public:
    int guessNumber(int n)
    {
        long long left = 1, right = n;
        long long pick = (left + right) / 2;
        while (geuss(pick) != 0)
        {
            if (geuss(pick) == -1)
            {
                right = pick;
            }
            else 
            {
                left = pick + 1;
            }
            pick = (left + right) / 2;
        }
        return pick;
    }
};